Pushers can be notoriously difficult to beat. You need to be patient and not get frustrated. You need to draw pushers to the net, they hate the net. Pushers generally love to run, so hitting at them can be successful as well.
But the most important thing to remember is not to overhit. It will often take more than one shot to put the ball away, sometimes even 3 or 4 great shots, that is why you cant over hit. I pusher only wins by the errors you make. A pusher can never hit a winner on you. I think Brad Gilbert was somewhat of a pusher. He made it to number 4 in the world. He was able to beat Boris Becker because Becker would get angry and lose his patience. Gilbert beat McEnroe at the master at Madision Square Garden one year. McBrat was so angry he took a sabbatical from tennis and actually said that Gilbert didnt even belong on the same court as him. Talk about sour grapes. Actually Gilbert was a master at using different games plans in order to defeat different style players. He wrote a book called Winning Ugly which is an excellent book and well worth the read.